Error propagation for barometers: 2. Application to rocks

A new evaluation is made of the uncertainty in pressure when a barometer is applied to an assemblage in a rock. Sources of error considered include: accuracy of the experimentally located, barometric end-member reaction, volume measurement errors, analaytical imprecision, uncertainty of electron microprobe standard compositions and α-factors, thermometer calibration errors, variation in garnet and plagioclase activity models, and compositional heterogeneity of natural minerals. Whereas calibration and analytical errors can be treated statistically, variability in activity models and natural compositional heterogeneity probably cannot be. -from Authors